Residence determination governs treaty residency and tie breaker rules, prioritising permanent home and centre of vital interests. Definition of resident depends on liability to tax by reason of domicile, residence, citizenship, place of management, place of incorporation, or similar criteria, excluding persons taxable only on in state source income and limiting partnerships, estates, or trusts to the extent their income is taxed as the income of a resident. Dual residency for individuals is resolved by a sequence of tests-permanent home, centre of vital interests, habitual abode, nationality, and mutual agreement-and dual residency for companies or other persons is resolved by specified treaty exceptions or by mutual agreement of competent authorities.